Engine surge (one example of engine combustion instability) includes oscillations in engine torque. Such oscillations in engine torque result in reduced drive feel.
In one approach a wheel brake pressure is controlled in response to measurements of engine torque. By increasing wheel brake pressure on one or more wheels in response to engine surge, vehicle traction may be improved during surge. Consequently, drivability may be improved.
The inventors herein have recognized issues with the above described approach. Controlling wheel brake pressure does not address the underlying engine conditions leading to engine surge. Without addressing the underlying engine conditions, engine surge may persist.
Consequently, systems, devices and methods are disclosed for engine control for a reformate engine. As one example, a method for an engine includes reforming fuel at a catalyst into reformate; and adjusting a supply of reformate to a cylinder of the engine in response to an engine surge, the surge including an oscillation in torque produced by the engine. The fuel to be reformed may include, for example, ethanol, another alcohol, gasoline, diesel fuel, or a combination of fuels.
One advantage of the example is that surge may be mitigated. Further, the present example allows for a smaller and lower cost reformer, if desired, because the supply of reformate to the engine cylinder is adjusted in response to surge, rather than continuously maintained at an unnecessarily high level during engine operation. By adjusting reformate in combination with further vehicle operating parameters, like charge dilution, wheel brake and spark timing, engine surge is mitigated while achieving increased engine efficiency due to aggressive use of lean burn, exhaust gas recirculation (EGR), and/or variable valve timing (VVT).
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description, which follows. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined by the claims that follow the detailed description. Further, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.